Power Controlled Microstructure and Infrared Properties of Air Plasma Spraying Based on YSZ Coatings

Yttria stabilized zirconia (YSZ) exhibits low thermal conductivity as well as high electrical conductivity in a high temperature environment, which plays an important role in the infrared stealth field. This work studied YSZ coatings with different porosities by controlling the spraying power of air plasma spraying (APS), while analyzing the influence of spraying power on the microstructure and crystalline structure of the YSZ coating, and the mechanism of porosity on the infrared emissivity of the YSZ coating. The results showed that the cross-sectional porosity decreased from 19% to 9% with a spraying power increase from 55 kW to 95 kW. However, the infrared emissivity of the coatings at 3-5 mu m decreased from 0.56 to 0.46 with porosity increases. Through the analysis of model simulation and theoretical calculation, it was found that YSZ coatings with higher porosity levels had more scatterers in the coating, which increased the backscattering of the coating and reduced the emissivity. The results showed that YSZ as a low emissivity coating has a dual effect and more potential in high temperature infrared stealth.